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Of the Six-Types of Asbestos, Chrysotile is Most Prevalent

Asbestos is a set of six naturally occurring silicate minerals exploited for commercial use. The inhalation of asbestos fibers can cause serious illnesses, including asbestosis, malignant mesothelioma, and lung cancer.

In January 2005, the European Union banned all use of asbestos and extraction, manufacture and processing of asbestos products.

There are six types: actinolite, amosite, anthophyllite, crocidolite, tremolite, and chrysotile asbestos. The first five types are called amphibolic asbestos, and are characterized by their very stiff fibers—making them especially dangerous when inhaled. The sixth type of asbestos, chrysotile, is called serpentine. Its fibers are much softer and more flexible than amphibolic asbestos and cause less damage to body tissue. All six types of asbestos are composed of long chains of silicon and oxygen atoms, locked with various metals, like magnesium and iron.

Chrysotile (added to concrete mixes and building materials) is the most commonly used type of asbestos, and accounts for approximately 95% of the asbestos found in buildings, according to the U.S. EPA Asbestos Building Inspectors Manual. It is sometimes known as white asbestos, although it can also be amber, gray, or greenish in color.

The only variety of serpentine asbestos, Chrysotile is present in a huge variety of materials including:

• drywall and joint compound
• plaster
• mud and texture coats
• vinyl floor tiles, sheeting, adhesives
• roofing tars, felts, siding, and shingles
• "transite" panels, siding, countertops, and pipes
• fire proofing
• caulk
• gaskets
• brake pads and shoes
• clutch plates
• stage curtains
• fire blankets
• interior fire doors
• fireproof clothing for firefighters
• thermal pipe insulation

Amosite asbestos, primarily used in insulation, often has a light brown tinge, but is also found in dark colors, as well as white. It accounts for 1% of world-wide production.

Crocidolite, often used as a reinforcement in plastics, is called blue asbestos and accounts for the remaining 1% of world-wide production.
Tremolite asbestos became well-known in Libby, Montana (EPA Superfund site) where thousands of residents became sick after years of exposure from town’s vermiculite mine. Under the trade name Zonolite, the vermiculite product was, and is in some cases, still being sold in housing insulation, brake lining and as a soil conditioner for gardens. It is mainly in the form of loose flakes that are shiny tan to golden-colored. Sometimes the flakes are shiny black and occasionally occur as clumps of flakes with the appearance of bellows on an accordion.

Listen to radio interview with journalists’ who led multi-year Libby investigation and authored, An Air That Kills.

The last types of asbestos—anthophyllite, actinolite—have no commercial applications and are rarely used.

Scientific Disagreement

In the past, scientists disagreed about the toxicity of amphibole versus serpentine asbestos fibers. Studies in both humans and animals have since demonstrated that both types of fibers increase the risk of asbestosis, malignant mesothelioma,  and lung cancer. Today, the scientific community agrees that amphiboles pose the greatest health hazard.